Combined finding and focusing mechanism for cameras.



J. E. WGODBURY.

COMBiNED FINDING AND FOCUSING MECHANISM FOR CAMERAS..

APPLICATION FILED NOV. 6, I912,

. 1,238,473. Pafnted Aug. 28,1917.

- fnz enfazw r1 u u l i h I hiine'ssgg 1 5 2 20 81 eiimEh oodzury fllwmmI a? 4 a! "l y flmmey JOHN E. woomap'nY, or WORCESTER, MASSACHUSETTS.

COMBINED FINDING AND FOCUSING MECHANISM FORCAMERAS.

, Specification of Letters Patent.

Patented Aug. 28, 1917.

Application filed November 6, 1912. Serial N 0. 729,772.

To "all whom it may concern:

Be it known that 1, JOHN E. WOODBU'RY, a citizen of the United States,residing at Worcester, in the county of Worcester and Commonwealth ofMassachusetts, have 1nvented a new and useful Improvement 1n a CombinedFinding and Focusing Mechanism for Cameras, of which the following,together with the accompanying drawing, is a specification. 1

My invention relates to a combined finding and focusing mechanism forcameras and one of its objects is to provide, in connection with afinder, mechanism to be operated by the movement of the lens inobtaining aposition suitable for focusing the image of an object upon aplate or film Within the camera, said mechanism acting to distort theimage seen in the finder at all times except when the lens is inposition to focus the corresponding image accurately upon the plate orfilm within the camera.

Another object of the invention is to provide' a compact finding andfocusing mechanism of this class.

so as to fold closely against one face of. the camera when not in use,with the advantage that in its folded'position it is more convenient tocarry about and is also less liable to damage.

Another object of. the invention is topros Vide' means whereby themechanism may be quickly and easily readjusted in case it loses itsaccuracy of adjustment while in use.

Further objects and advantages will appear from the followingdescription taken in connection with theaccompanylng drawbeing brokenaway; Fig. .5is a view of an image in the finder as the image looks whenthe lens is out of correct focusing position; and Fig. 6 is a Viewsimilar to that shown in Fig.5 except that it shows the image as itappears when the lens is in correct focusing position. I

In accomplishing this object the mechanism has been constructed.

. Like reference characters indicate similar parts in the differentfigures.

In the diagrammatic view shown in Fig. 1 the lens 1 serves as a directview finder in a manner well known to those familiar with the art. Infront of the lens 1 is a small mirror 2 placed at an angle of 45, orthereabout, to the axis of the lens. At one side of this lens and mirroris another mirror 3 with its face parallel, or nearly so, to the face ofthe mirror 2. The" reflecting surfaces of the two mirrors face eachother. The lens 1 and the mirror 2 are fixed in position, but the mirror3 is adjustable about a vertical axis at its edge nearest the lens.Mounted upon a pivot 4 is a lever 5 including arms 6 and 7 the free endof the arm 7 carrying a cam 8 which engages a pin- 9 attached to theadjustable mirror 3 so that this lever 5 and cam 8 may control theposition of this mirror.

To the free end of the arm 6 is attached one-end of a link 10, the otherend of this link being pivotally. attached to some portion of the camerawhich moves forwardly and backwardly with the camera lens as the saidlens is adjusted in position to obtain a correct focus. coincides withthe line AA so that, in viewing a scene to be photographed the rays oflight from the center of the scene will pass along this line AA. If thescene be va distant one, several hundred feet from the camera forinstance, the rays of light from the center of the scene will also passalong the line BB, this line being practically parallel to the line AA.The small mirror 2 is located with its center approximately at the lineAA so as to intercept a small amount of light which would otherwise formthe central portion of the image seen through the lens 1. The lens andthe two mirrors are, however, so adjusted in relative position that therays of light traveling along the line BB are reflected first to themirror 2 and from there along the line AA through the lens 1.

The lines AA and BB point to the same portion of the scene to bephotographed and, therefore, the rays of light traveling along these twolines are exact-1y similar and, for this reason, it is obvious that thelight reflected by the two mirrors will exactly and symmetrically fillin the small portion of the directly formed image which was blotted outby the mirror 2. If,

The axis of the lens 1 now, the adjustable mirror 3 be changed inposition, it is clear that the image reflected thereby through the lens1 by Way of the mirror 2 will be shifted in position relatively to thatportion of the image which is formed directly. It will be seen that,when the camera is pointed toward a distant object, all that isnecessary in order to obtain a proper focus is to draw out the lensuntil the cam 8 has moved the mirror 3 into such position that thecenter of the image seen in the mirror 2 through the lens I 1 is inexact register with the remaining portion of the image which is directlyformed.

Suppose, now, that the line CC intercepts the line AAv at a point tenfeet from the'camera. The shape of the cam 8 is such that, with the lenschanged in position so as to focus this nearer object properly, themirror 3 will be moved into a position,as shown in dotted lines, toreflect the light coming along this line CC through the lens 1 by way ofthe mirror 2 in a manner exactly similar to .that which has been alreadydescribed.

In shaping the cam 8, the cam, together with the remainder of the'finding and focusing mechanism which has been described, may be mountedupon the camera while the working edge of the cam is still The cameramay then be focused upon a suitable object at a known distance from thecamera by means of a focusing screen located within the camera in theusual manner. The working edge of the cam, at the point which contacts.with the pin 9, may then be carefully worked down with a fine file andoilstone, or other suitable tools, until the adjustable mirror 3 isallowed to assume such position that the portions of the image seen inthe finder c0- incide, as shown in Fig. 6. This operation may then berepeated, the object upon which the camera is focused being located atdifferent distances from the camera, until a suflicient number of pointsalong the edge of the cam have been worked down to make its working edgea practically smooth curve.

Thus far the lens may be positioned to obtain accurate focusing powerfor very distant objects and for objects ten feet from the camera. Inlike manner the mirror 3 is adjusted in position by moving the lens ofthe camera so that objects at all distances within the range of thecamera may be properly focused merely by moving 'the lens of the camera,observing the direct and reflected portions of the image through thelens 1 until these two portions register exactly.

In Fig. 5 is shown a view of the lens 1 and the mirror 2 as seen throughthe lens 1.

The line DD represents any object,

such as a flagpole, to be photographed, but the fact that the portion ofthe image shown in the mirror 2 is not in line with those portions seendirectly through the lens 1 shows that the camera lens is not inposition to focus properly the rays of light from the object upon theplate or film within the camera.

Fig. 6 shows the appearance of the image through the lens 1 when thecamera lens has been moved into proper focusing osition, the cam 8,controlled by the position of the camera lens, having moved theadjustable mirror 8 so that the reflected portion of the image shown inthe mirror 2 exactly registers with the unreflected portions thereof.

Referring now to Figs. 2, 3 and 4:, which indicate one construction bymeans of which my invention maybe practised, the lens 1 serves in acommon and well known manner as a direct view finder. The small mirror 2is supported in angular position in front of the lens 1 by a small armextending from and rigidly attached to or integral with a frame '11holding the lens 1. The frame 11 with the lens 1 and'mirror 2 'carriedthereby is supported at three points in the main frame or support 12.One side of this frame 11 carries a pin 13 which fits snugly in a smallhole provided therefor in the end of the frame'12. The opposite side ofthe frame 11 is provided with a flange 14 which is engaged by a pair ofscrews 15 having their heads seated in the frame 12. Attached to thefront face of the frame 12 is a spring 16, the free end of which pressesagainst the rear face of the flange 14 in order to cooperate with thescrews 15 in holding the lens 1 and mirror 2 accurately in'place. Itwill be seen that, within reasonable limits, the positions of the lens 1and mirror 2 may be accurately adjusted in any direction by turning oneor the other, or both, of the screws 15.

The mirror 3 is mounted upon the pivot 17 and carries the pin 9,projecting below its lower edge, to engage the cam 8 so that this cammay control the angular position of the mirror 3 about the pivot 17.. Aspring 18 holds the pin 9 against -the cam 8. The cam 8 and the arm 7are each rigidly attached to a shaft passing through the top of thecamera, this cam 8 and arm 7 together with the shaft connecting them andthe arm 6 constituting the lever 5. The free end of the arm 6 isconnected by the link 10 to the lens board 19, or any other suitableportion pf the camera which moves with the camera ens.

The parts of the structure which have been described correspond to thosepreviously described in connection with the diagrammatic view shown inFig. 1 and thesame reference characters have been used where possible;

and from the description given in connection with Fig. 1, the principleof the operation of the actual mechanism which has just been describedwill be apparent.

In order thatmy device may be folded into as convenient form as possiblewhen not in use, the main frame or support 12 carrying the lens 1 andthe mirrors 2 and 3 is attached to the top of the camera box by hinges20. By rotating the mirror 3 about its pivot 17 and into the plane ofthe frame 12, the frame 12 and the parts carried thereby may be foldeddown forwardly onto the top of the camera box. A small opening or recess21 in the top of the camera box receives the small mirror 2 when thedevice is in folded position. A suitable track orcam way 22 1s providedin the surface of the camera box under the pin 9 so that, as the frame12 is tipped forwardly about the hinges 20, the lower end of this pin 9will engage the cam way 22, the cam way forcing the pin rearwardly andupwardly as the frame 12 is tipped until finally the mirror 3 has beenrotated into the plane of the frame 12. This is a matter of considerableconvenience, allowing one to fold the frame 12 against the top of thecamera without first having to draw back the mirror 3, the cam way 22acting automatically tmaccomplish this result.

A short arm 23 extends rearwardly from the pivoted edge of the mirror 3to provide manually operable means for accomplishing the same result forwhich the cam way 22 is intended. A singleforward pressure against thisarm 23 will rotate the mirror 3 into the lane of the frame 12 and willalso tip the rame 12 down onto the top of the camera box. In order tohold the frame 12 with the lens and mirrors carried thereby in properoperative position, a small stop 24 is provided under the rear edgethereof to limit its motion as it is opened, and a spring 25 attached tothe top of the camera box presses against the lower front edge of thisframe to hold it either against the stop 24 when in open position,or'against the top of the camera box when in folded position..

A stop 26 fastened securely to the track carrying the lens board servesto determine accurately the position of the lens for properly focusingthe images or other distant objects, that is, objects more than onehundred feet, or thereabout, from the camera. By means of this stop 26the accuracy with which the device is performing its function may betested very quickly and easily. By drawing out the lens until the stop26 is reached, it is known that the lens "is in proper position to focusproperly images or distant objects, and if, now, the direct andreflected portions of the image of such objects as seen through the lens1 register accurately as shown in Fig. 6, then the device is in properadjustment; but if these two portions of the image do'not registeraccurately as shown in Fig. 5, then the device is out of adjustment.When it is found in this way that readjustment is necessary, thepositions of the lens 1 and mirror 2 may be adjusted by turning one orthe other, or both, of the screws 15 until the two portions of the imageseen through the lens 1 register exactly. Having provided the properadjustment for distant objects, or objects at any known distance, andthe shape of the cam having been accurately designed, then the devicewill be in proper adjustment for all other distances within the range ofthe camera. In ordinary use the camera lens is drawn out until the stop26 is reached and then, if the object to bephotographed is less than onehundred feet or so from the camera, the ordinary rack and pinioncontrolled by the thumb nut 27 is used.

The image seen through a direct view finder, such as the lens 1, canrepresent accurately the scene which the camera is in position tophotograph only when the image is being viewed exactly along the axis ofthe view finder. Such image is approximately correct if viewed from someother point and it may be that it is sufliciently accurate for somepurposes if viewed from any point from which it may be reasonablyclearly seen. I

It is many times desirable and often necessary, however, to see in theview finder the exact image which the camera is in position to take. Asmall spot 28 is, therefore, placed upon the center of the mirror 3 andthe lens 1 is provided with a cross in the usual manner. When this spot28 is seen exactly at the intersection of the lines of the cross on thelens 1, it is certain that the scene which the camera is in position tophotograph is indicated accurately by the image shown in the viewfinder. While it is preferable to place the-spot 28 upon the mirror 3,the same result is accomplished by placing it upon the mirror 2,although the latter arrangement is not as satisfactory, being lesssensitive.

An important feature of the invention resides, in the location of thelens 1 and both the mirrors 2 and 3 upon the same rigid support, theparts being much easier to keep in adjustment than would be the casewere the mirrors mounted on separate supports-,1. V 120 The mirror 3,rather than the mirror 2, is arranged to be adjusted in position inaccordance with the focusing movements of the lens because a givenangular movement of the mirror 3 will shift the reflected image, as seenthrough the lens 1, to a greater extent than would the same angulardisplacement of the mirror 2 and the device is therefore madeconsiderably more reliable. This is for the reason that the greater themovement of the mirror, the more accurately can its movements becontrolled and the less effect will any inaccuracy in the shape of byLetters Patent is:

1. In a focusing device for cameras, the combination with an opticalgroup constituting a distance finder and comprising two reflectorsadapted to jointly form a complete image and means movable with thecamera lens for varying the relationship of light rays that produce thecomponents of said image, of a support for one of the re flectorsadjustably cooperating therewith at two points to rock it transverselyof its general plane to different positions about a third point as acenter.

2. In a focusing device for cameras, the combination with an opticalgroup constituting a distance finder and comprising two reflectorsadapted to jointly form a complete image and means movable with thecamera lens for varying the relationship of light rays that produce thecomponents of said image, of a support for one of the reflectorscomprising a universal pivot and two adjusting screws by means of whichlatter the reflector may be turned transversely of its general plane onthe pivot about different axes.

3. In a focusing device for cameras, the combination with an opticalgroup constituting a distance finder and comprlsing two reflectors and alens fixed with relation to one of them, the reflectors being adapted tojointly form a complete image in the lens, and means movable with thecamera lens for varying the relationship of light rays that produce thecomponents of said image, of a common sup ort for the finder lens andthe relatively xed reflector comprisin a universal pivot and twoindependent ad justing devices by means of which latter the saidreflector and lens may be turned on the pivot about different axestransverse to the axis of the finder lens. 4. In combination, a camera,a frame, and a finder and two mirrors mounted on the frame, one of themirrors being pivoted thereto and normally at an angle to the plane ofthe frame, the frame being pivoted to the camera to fold toward one ofits faces, and means to rotate the pivoted mirror into the plane of theframe to permit the frame to be folded.

5. In combination, a camera, a frame, and a finder and two mirrorsmounted on the frame, one of the mirrors being pivoted thereto andnormally at an angle to the plane of the frame, the frame being pivotedto the camera to fold toward one of its faces, and automatic means torotate the pivoted mirror, into the plane of the frame to permit theframe to be folded.

6. In combination, an exteriorly' arranged camera, a frame, pivoted tothe camera to fold toward one face thereof, and finding and focusingmechanism mounted upon the frame.

7. In combination, a camera, a frame, a finder, a mirror within thefield of View of said finder and a second mirror without said field ofview, said finder and mirrors being mounted on said frame, one of saidmirrors being adjustable and being connected to the camera lens to beadjusted in position as the camera lens is moved in focusing, the framebeing pivoted to the camera to rotate into and out of operativeposition.

8. In combination, a camera, a frame pivoted to the camera, findingmechanism mounted on the frame, focusing mechanism pivoted to the frameand normally at an angle to the plane of the frame, the focusingmechanism being rotatable into the plane of the frame to permit theframe to be folded toward a face of the camera.

9. In combination, a camera, a frame pivoted to the camera, findingmechanism mounted on the frame, focusing mechanism pivoted to the frameand normally at an angle to the plane of the frame, and means forrotating the focusing mechanism into the plane of the frame to permitthe frame to be folded toward a face of the camera.

10. In combination, a camera, a frame pivoted to the camera, findingmechanism mounted on the frame, focusing mechanism pivoted to the frameand normally at an angle to the lane of the frame, and automatic meansor rotating the focusing mechanism into the plane of the frame to ermitthe frame to be folded toward a ace of the camera.

11. In a focusing device for cameras, the combination with a camerabody, camera lens and lens carriage, of a distance finder mountedexteriorly of the camera body and consisting of an optical groupincluding a variable element and connections extending within the camerabody between the said variable element and the lens carriage.

12. In a focusing device for cameras, the combination with a camerabody, camera lens and lens carriage, of a distance finder mounted on thecamera body and consisting of an optical group includinga variableelement and detachable connections between the said variable element andthe lens carriage.

13. In a focusing device for cameras, the combination with a camerabody, of a focusing finder embodying a lens and two angle mirrorsadapted to jointly direct an image to the lens, one of the mirrors beingfoldable to a position in the plane of the lens.

14. In a focusing device for cameras, the combination with a camerabody, of a focusing finder mounted thereon and embodying a lens havingan operative'position at an angleto a wall of the body and a foldedposition against said wall and also embody- 1o ing two angle mirrorsadapted to jointly direct an image to the lens, one of the mirrors beingfoldable to a position in the plane of the lens.

JOHN E. WOODBURY, Witnesses:

PENELOPE COMBERBAOH, NELLIE-WHALEN.

